Some wireless communication standards have a spectrum allocation of multiple wireless channels (frequency bands), where each channel has a distinct functionality and where several channels need to be processed concurrently. The channels are completely independent, receiving packets from different sources at different times. For example, the vehicle-to-vehicle (V2V) communication IEEE standard has seven allocated channels, of which one is allocated for safety and others for services. Concurrent reception of both the safety channel and of a service channel is required.
Antenna diversity is a well-known method to improve the communication quality. Some implementations combine the signals from all antennas for maximal reception quality. This approach is called “full diversity”. Other implementations use only a subset of the antennas, since the number of processing elements denoted as “receivers” is lower than the number of antennas. The field of “switching diversity” or “switched diversity” involves studies of preferred antenna selection methods. A full diversity solution is more expensive than a switching diversity solution, because the size and complexity of full diversity implementation are higher. However, full diversity provides better communication quality.
The switching diversity theory is focused on receiving a single source of data (single channel) at a time. However, in some communication environments such as V2V, independent data links are handled concurrently in different channels. Each channel uses a different frequency.
Some V2V communication installations (or “systems”) mandate the use of two antennas for omni-directional antenna pattern. For full diversity implementation of two channels, the number of receivers has to be twice the number of channels, as two receivers have a fixed allocation to one channel. For example, a vehicle can use a single antenna if the antenna is positioned on the top of its roof. Other vehicles, like vehicles without observable antennas, need two antennas positioned either on windows, bumpers or side-mirrors.
The term “dynamic control” with reference to receivers is known. Dynamically controlled diversity receivers are capable of performing various diversity receiving and processing schemes, however involving only one channel. The term “dynamic control” with reference to a receiver also refers to the configuration and capability of a receiver to select one or two antennas for reception of a single channel.
FIG. 1A illustrates a known wireless communication system 100 that supports reception of two channels with full antenna diversity. System 100 includes exemplarily two antennas A and B that serve two channels. Each antenna covers a partial antenna. Together, the two antennas provide omnidirectional pattern. A splitter and combiner “block” per antenna (respectively blocks 102 and 104) is needed to operate two different channels with a single antenna. The splitter and combiner block is used to reduce the number of antennas. For example, blocks 102 and 104 could be dispensed with if four antennas were implemented and each antenna was routed directly to a receiver. Four receivers 106, 108, 110 and 112 are needed for implementation of full availability of this scheme. System 100 further includes two “full diversity” receivers 114 and 116, each receiving two antennas and performing full diversity reception. Each receiver outputs a respective channel, respectively channels 1 and 2. Such a system is feasible but expensive and requires a large physical size.
FIG. 1B illustrates a known wireless communication system 100′ that supports reception of two channels with switched antenna diversity. System 100′ is similar to system 100 but includes two diversity switches 122 and 124 coupled respectively to two “regular” receivers 126 and 128 instead of the two full diversity receivers 114 and 116. Each diversity switch receives two antennas and selects one antenna for processing at the respective receiver. Each receiver processes a single antenna and outputs a single channel (respectively channels 1 and 2) but does not provide receiver gain. The switching control is described in known switched diversity art. Such a system is feasible but shows limited performance where diversity gain is needed.
There is therefore a need for, and it would be highly desirable to have systems and related methods that handle multiple channels with dynamically controlled diversity reception, i.e. with a number of receivers that is smaller than twice the number of channels, to reduce system cost and size.